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WARNING
The temperature grade for this tire is
established for a tire that is properly
inflated and not overloaded.
Excessive speed, under-inflation,
over-inflation, or excessive loading,
either separately or in combination,
can cause heat build-up and
possible sudden tire failure. This
may cause loss of vehicle control
resulting in an accident.
Tire Terminology and Definitions
Air pressure
The amount of air inside the tire
pressing outward on the tire. Air
pressure is expressed in pounds per
square inch (psi) or kilopascal (kPa).
Accessory weight
This means the combined weight
of optional accessories. Some
examples of optional accessories
are automatic transmission, power
seats, and air conditioning.
Aspect ratio
The relationship of a tire’s height to
its width.
Belt
A rubber coated layer of cords that
is located between the plies and the
tread. Cords may be made from steel
or other reinforcing materials.
Bead
The tire bead contains steel wires
wrapped by steel cords that hold the
tire onto the rim.
Bias ply tire
A pneumatic tire in which the plies are
laid at alternate angles less than 90
degrees to the centerline of the tread.
Cold tire pressure
The amount of air pressure in a tire,
measured in pounds per square inch
(psi) or kilopascals (kPa) before a tire
has built up heat from driving.
Curb weight
This means the weight of a motor
vehicle with standard and optional
equipment including the maximum
capacity of fuel, oil and coolant, but
without passengers and cargo.
DOT markings
A code molded into the sidewall
of a tire signifying that the tire
is in compliance with the U.S.
Department of Transportation motor
vehicle safety standards. The DOT
code includes the Tire Identification
Number (TIN), an alphanumeric
designator which can also identify
the tire manufacturer, production
plant, brand and date of production.
GVWR
Gross Vehicle Weight Rating
GAWR FRT
Gross Axle Weight Rating for the
Front Axle.
GAWR RR
Gross Axle Weight Rating for the
Rear axle.
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Maintenance
Intended outboard sidewall
The side of an asymmetrical tire,
that must always face outward when
mounted on a vehicle.
Kilopascal (kPa)
The metric unit for air pressure.
Light Truck (LT) tire
A tire designated by its manufacturer
as primarily intended for use on
lightweight trucks or multipurpose
passenger vehicles.
Load ratings
The maximum load that a tire is rated
to carry for a given inflation pressure.
Load index
An assigned number ranging from 1
to 279 that corresponds to the load
carrying capacity of a tire.
Maximum inflation pressure
The maximum air pressure to which
a cold tire may be inflated. The
maximum air pressure is molded
onto the sidewall.
Maximum load rating
The load rating for a tire at the
maximum permissible inflation
pressure for that tire.
Maximum loaded vehicle weight
The sum of curb weight; accessory
weight; vehicle capacity weight; and
production options weight.
Normal occupant weight
The number of occupants a vehicle
is designed to seat multiplied by 150
pounds (68 kg).
Occupant distribution
Designated seating positions.
Outward facing sidewall
An asymmetrical tire has a particular
side that faces outward when
mounted on a vehicle. The outward
facing sidewall bears white lettering
or bears manufacturer, brand, and/or
model name molding that is higher
or deeper than the same moldings
on the inner facing sidewall.
Passenger (P-Metric) tire
A tire used on passenger cars
and some light duty trucks and
multipurpose vehicles.
Ply
A layer of rubber-coated parallel
cords.
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Pneumatic tire
A mechanical device made of rubber,
chemicals, fabric and steel or other
materials, that, when mounted on
an automotive wheel provides the
traction and contains the gas or fluid
that sustains the load.
Pneumatic options weight
The combined weight of installed
regular production options weighing
over 5 lb. (2.3 kg) in excess of the
standard items which they replace,
not previously considered in
curb weight or accessory weight,
including heavy duty breaks, ride
levelers, roof rack, heavy duty
battery, and special trim.
Recommended inflation pressure
Vehicle manufacturer’s
recommended tire inflation pressure
as shown on the tire placard.
Radial ply tire
A pneumatic tire in which the ply
cords that extend to the beads are
laid at 90 degrees to the centerline
of the tread.
Rim
A metal support for a tire and upon
which the tire beads are seated.
Sidewall
The portion of a tire between the
tread and the bead.
Speed rating
An alphanumeric code assigned to a
tire indicating the maximum speed
at which a tire can operate.
Traction
The friction between the tire and
the road surface. The amount of grip
provided.
Tread
The portion of a tire that comes into
contact with the road.
Treadwear indicators
Narrow bands, sometimes called
“wear bars”, that show across the
tread of a tire when only 1/16 inch of
tread remains.
UTQGS
Uniform Tire Quality Grading
Standards is a tire information
system that provides consumers
with ratings for a tire’s traction,
temperature and treadwear.
Ratings are determined by tire
manufacturers using government
testing procedures. The ratings are
molded into the sidewall of the tire.
Vehicle capacity weight
The number of designated seating
positions multiplied by 150 lbs. (68
kg) plus the rated cargo and luggage
load.
Vehicle maximum load on the tire
Load on an individual tire due to curb
and accessory weight plus maximum
occupant and cargo weight.
Vehicle normal load on the tire
Load on an individual tire that is
determined by distributing to each
axle its share of the curb weight,
accessory weight, and normal
occupant weight and dividing by 2.
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